# Reliable Automated Displacement Monitoring Using Robotic Total Station Assisted by a Fixed-Length Track

## TL;DR

This paper introduces a cost-effective method for reliable displacement monitoring using a robotic total station and a fixed-length track.

## Contribution

A novel automated displacement monitoring method using a single robotic total station with a fixed-length track is proposed.

## Key findings

- The proposed method achieves forward intersection with a single robotic total station, reducing costs.
- The accuracy of forward intersection improves over polar coordinate methods as monitoring distance increases.
- The robotic total station reliably finds and aims at targets while moving on the track.

## Abstract

Robotic total stations are multi-sensor integrated instruments widely used in displacement monitoring. The principles of polar coordinate or forward intersection systems are usually utilized for calculating monitoring results. However, the polar coordinate method lacks redundant observations, leading to unreliable results sometimes. Forward intersection requires two instruments for automated monitoring, doubling the cost. In this regard, this paper proposes a novel automated displacement monitoring method using the robotic total station assisted by a fixed-length track. By setting up two station points at both ends of a fixed-length track, the robotic total station is driven to move back and forth on the track and obtain observations at both station points. Then, automated monitoring based on the principle of forward intersection with a single robotic total station is achieved. Simulation and feasibility tests show that the overall accuracy of forward intersection is better than that of polar coordinate system as the monitoring distance increases. At the same time, regardless of tracking a prism or not, the robotic total station is able to automatically find and aim at the targets when moving between station points on the track. Further practical tests show that the reliability of the monitoring results of the proposed method is superior to the polar coordinate method, which provides new ideas for ensuring the reliability of results while reducing cost in actual monitoring tasks.